A gyrolaser is a velocity sensor that uses a laser ray. It is used to measure angular rotation velocities of a mobile carrier. This type of equipment is notably used for aeronautical applications.
The gyrolaser, developed some thirty years ago, is widely marketed and used these days. Its operating principle is based on the Sagnac effect, which induces a frequency difference between two optical emission modes being propagated in opposite directions, called counter-propagating, in a laser cavity in the form of a bidirectional ring driven by a rotational movement. The laser cavity, generally square or triangular, is equipped at each of its corners with mirrors reflecting the two emitted signals.
On any gyrolaser, a number of locking loops are necessary to the optimal operation of the sensor in order to provide an optical signal containing angular velocity information concerning the mobile. There is thus:                a cavity length locking loop whose function is to maintain the internal length of the cavity at a value that is a multiple of the wavelength of the two optical modes,        an activation locking loop which aims to maintain an oscillatory movement making it possible to minimize the well-known blind region phenomenon,        a laser powers locking loop which makes it possible to maintain the two optical signals at a constant level upstream of the angular velocity computation processing operations,        a plasma discharge current locking loop making it possible to maintain a predefined current that is equal in each cavity.        
In the known gyrolasers, a significant portion of these locking subsystems is implemented by analogue means which brings with it significant card surface area and limited reliability problems.
Furthermore, the activation locking loop generally uses a detection device placed on the activation wheel, for example a piezo-transducer, the transfer function of which may vary over time and lead to undetectable faults which will affect the activation locking mechanism with errors.
The present invention proposes, in order to mitigate the abovementioned problems, a solution making it possible to significantly reduce the manufacturing costs by reducing the analogue shaping stages and by eliminating the movement detection devices of the activation locking subsystem.
The proposed solution makes it possible, through a digitization of all of the processing operations, to optimize the integration and increase the reliability of the system. Finally, it makes it possible to guarantee excellent activation amplitude stability and to improve the long-term bias performance levels of the sensor, notably in the case of poorly compensated or uncompensated spurious movements.